The present invention relates generally to the field of robotics and specifically to robotic tool coupling device.
Robots are widely utilized in industrial assembly line applications to perform repetitive tasks very precisely without the need for human operation, interaction, or supervision. For example, robots are commonly used in the automotive industry to perform a number of tasks such as material handling and spot-welding of automobile bodies.
To amortize the considerable cost of an industrial robot over a variety of tasks, the robot arm is typically separate from a diverse array of tools, which are removably attached to the end of the robot arm. To facilitate this plurality of tools, each robot arm typically terminates in a coupling device, referred to as a “master” device or master plate. A corresponding “tool” device or tool plate is connected to each tool that may be attached to the robot arm. A coupling mechanism positively locks the master and tool plates together for the duration of the use of the tool on the robot arm, and releases the tool from the robot arm upon completion of the tool's task(s). The coupling mechanism may additionally provide for the transfer of services from the robot arm to the tool, such as electrical power, pneumatic fluid, or the like.
The use of rolling members, urged by a piston against an inclined surface, to lock the master and tool plates together is well known in the art. For example, U.S. Pat. No. 4,696,524 discloses a plurality of ball members contained within the tool plate, and circumferentially arranged around a central axis. Extending from the master plate, along this axis, is a piston member operative to contact the ball members and urge them outwardly. The ball members contact a surface disposed at an angle such that outward force induced on the ball members by the piston generates an upward force component that presses the angled surface, and thus the entire tool plate, against the master plate.
U.S. Pat. No. 5,211,501 discloses a substantially similar piston and ball member arrangement, with an improved piston/ball member contact surface. This patent discloses a multifaceted contact surface comprising an initial tapered contact surface for first contacting the ball members and moving them outward and into contact with an angled surface. A flat failsafe surface is adjacent the initial tapered surface. A final tapered surface, at an angle with respect to the axis of less than that of the initial actuating surface, is adjacent the failsafe surface. The final tapered surface presses the ball members into the angled surface(s), and locks the tool plate to the master plate.